Intracellular protein degradation by the ubiquitin-proteasome system is ATP dependent, and the optimal ATP concentration to activate proteasome function in vitro is -100 μM. IntraceUular ATP levels are generally in t...Intracellular protein degradation by the ubiquitin-proteasome system is ATP dependent, and the optimal ATP concentration to activate proteasome function in vitro is -100 μM. IntraceUular ATP levels are generally in the low millimolar range, but ATP at a level within this range was shown to inhibit proteasome peptidase activities in vitro. Here, we report new evidence that supports a hypothesis that intracellular ATP at the physiological levels bidirectionally regulates 26S proteasome proteolytic function in the cell. First, we confirmed that ATP exerted bidirectional regulation on the 26S proteasome in vitro, with the optimal ATP concentration （between 50 and 100μM） stimulating proteasome chymotrypsin-like activities. Second, we found that manipulating intracellular ATP levels also led to bidirectional changes in the levels of proteasome-specific protein substrates in cultured cells. Finally, measures to increase intracellular ATP enhanced, while decreasing intraceHular ATP attenuated the ability of proteasome inhibition to induce cell death. These data strongly suggest that endogenous ATP within the physiological concentration range can exert a negative impact on proteasome activities, allowing the cell to rapidly upregulate proteasome activity on ATP reduction under stress conditions.展开更多
Background:We previously found that overexpression of the gene known as amplified in breast cancer 1(AIB1)was associated with lymph node metastasis and poor prognosis in patients with lung adenocarcinoma.However,the r...Background:We previously found that overexpression of the gene known as amplified in breast cancer 1(AIB1)was associated with lymph node metastasis and poor prognosis in patients with lung adenocarcinoma.However,the role of AIB1 in that malignancy remains unknown.The present study aimed to investigate the function of AIB1 in the process of lung adenocarcinoma cell metastasis.Methods:A series of in vivo and in vitro assays were performed to elucidate the function of AIB1,while real-time PCR and Western blotting were utilized to identify the potential downstream targets of AIB1 in the process of lung adenocarcinoma metastasis.Rescue experiments and in vitro assays were performed to investigate whether the invasive-ness of AIB1-induced lung adenocarcinoma was mediated by C-X-C motif chemokine receptor 4(CXCR4).Results:The ectopic overexpression of AIB1 in lung adenocarcinoma cells substantially enhanced cell migration and invasive abilities in vitro and tumor metastasis in vivo,whereas the depletion of AIB1 expression substantially inhibited lung adenocarcinoma cell migration and invasion.CXCR4 was identified as a potential downstream target of AIB1 in lung adenocarcinoma.The knockdown of AIB1 greatly reduced CXCR4 gene expression at both the transcription and protein levels,whereas the knockdown of CXCR4 in cells with AIB1 ectopic overexpression diminished AIB1-induced migration and invasion in vitro and tumor metastasis in vivo.Furthermore,we found a significant positive association between the expression of AIB1 and CXCR4 in lung adenocarcinoma patients(183 cases),and the co-overexpression of AIB1 and CXCR4 predicted the poorest prognosis.Conclusions:These findings suggest that AIB1 promotes the aggressiveness of lung adenocarcinoma in vitro and in vivo by upregulating CXCR4 and that it might be usable as a novel prognostic marker and/or therapeutic target for this disease.展开更多
基金Acknowledgments This work was supported by the National High Technol- ogy Research and Development Program of China （Project 2006AA02Z4B5）, the National Natural Science Foundation of China （Project 2010）, and a Key Project （9251018201002） of Guangdong Province Natural Science Foundation （to JL）. It was also supported in part by Grants HL072166, HL085629, and HL068936 of the NIH and an Established Investigator Award （0740025N） of the American Heart Association （to XW）.
文摘Intracellular protein degradation by the ubiquitin-proteasome system is ATP dependent, and the optimal ATP concentration to activate proteasome function in vitro is -100 μM. IntraceUular ATP levels are generally in the low millimolar range, but ATP at a level within this range was shown to inhibit proteasome peptidase activities in vitro. Here, we report new evidence that supports a hypothesis that intracellular ATP at the physiological levels bidirectionally regulates 26S proteasome proteolytic function in the cell. First, we confirmed that ATP exerted bidirectional regulation on the 26S proteasome in vitro, with the optimal ATP concentration （between 50 and 100μM） stimulating proteasome chymotrypsin-like activities. Second, we found that manipulating intracellular ATP levels also led to bidirectional changes in the levels of proteasome-specific protein substrates in cultured cells. Finally, measures to increase intracellular ATP enhanced, while decreasing intraceHular ATP attenuated the ability of proteasome inhibition to induce cell death. These data strongly suggest that endogenous ATP within the physiological concentration range can exert a negative impact on proteasome activities, allowing the cell to rapidly upregulate proteasome activity on ATP reduction under stress conditions.
基金supported by grants from National Key R&D Program of China(No.2017YFC1309001)Nature Science Foundation of China(No.81201842 and No.81772483)Open Project of State Key Laboratory of Respiratory Disease of China(No.SKLRD2016OP004 and No.2007DA80154F1108).
文摘Background:We previously found that overexpression of the gene known as amplified in breast cancer 1(AIB1)was associated with lymph node metastasis and poor prognosis in patients with lung adenocarcinoma.However,the role of AIB1 in that malignancy remains unknown.The present study aimed to investigate the function of AIB1 in the process of lung adenocarcinoma cell metastasis.Methods:A series of in vivo and in vitro assays were performed to elucidate the function of AIB1,while real-time PCR and Western blotting were utilized to identify the potential downstream targets of AIB1 in the process of lung adenocarcinoma metastasis.Rescue experiments and in vitro assays were performed to investigate whether the invasive-ness of AIB1-induced lung adenocarcinoma was mediated by C-X-C motif chemokine receptor 4(CXCR4).Results:The ectopic overexpression of AIB1 in lung adenocarcinoma cells substantially enhanced cell migration and invasive abilities in vitro and tumor metastasis in vivo,whereas the depletion of AIB1 expression substantially inhibited lung adenocarcinoma cell migration and invasion.CXCR4 was identified as a potential downstream target of AIB1 in lung adenocarcinoma.The knockdown of AIB1 greatly reduced CXCR4 gene expression at both the transcription and protein levels,whereas the knockdown of CXCR4 in cells with AIB1 ectopic overexpression diminished AIB1-induced migration and invasion in vitro and tumor metastasis in vivo.Furthermore,we found a significant positive association between the expression of AIB1 and CXCR4 in lung adenocarcinoma patients(183 cases),and the co-overexpression of AIB1 and CXCR4 predicted the poorest prognosis.Conclusions:These findings suggest that AIB1 promotes the aggressiveness of lung adenocarcinoma in vitro and in vivo by upregulating CXCR4 and that it might be usable as a novel prognostic marker and/or therapeutic target for this disease.
